1. Field of the Invention
The present invention relates to a dry powder formulation useful to make a fountain solution for use in lithographic printing operations and to a method of making a fountain solution from a dry powder formulation for use in lithographic printing. More particularly the invention relates to such a dry powder formulation which can be combined with water in situ to formulate a fountain solution concentrate or press ready fountain solution for lithographic printing applications.
2. Description of the Prior Art
In lithographic printing processes, such as in lithographic printing of newspapers, brochures and the like, fountain solutions are used in lithographic presses to replenish the desensitized area of lithographic plates, to clean the surface of the plates and to continuously keep the non-printing area of such plates water receptive or hydrophilic.
Prior to the present invention, fountain solutions were formulated which were acid based and included pure gum arabic, bichromate and phosphoric acid. These acid solutions had been used in the formulation of desensitizers or etches for stone lithography, zinc plate lithography and photo lithography on both zinc and aluminum. However, with the introduction of rotary lithographic sheet fed presses, the ability to feed ink and water in a continuous fashion to the surface of the plate led to the development of acid and gum treated solutions which would continuously replenish the desensitized area of the lithographic plate. Solutions of this type provided the ability to lithograph in a continuous and uninterrupted fashion. Drawbacks to using this type of formulation are the fact that bichromates link with phosphoric acid and gum to produce desensitizers which, while effective, are also capable of being absorbed and maintained in the human body and after sufficient absorption may produce serious skin rashes. In addition these types of fountain solutions had to be made up or mixed at each lithographic plant and hence there was the possibility of mistakes in the formulation which would effect the lithographic printing process.
More recently, alkali fountain solutions have been developed and have found wide commercial applicability for use in modern high speed newspaper web offset presses. These types of lithographic presses need fountain solutions without gum arabic or synthetic gums as desensitizers as the gums have a tendency in high speed operation to accumulate on the blankets and ink rollers and create a glaze condition on the ink rollers tending to cause the ink to strip from the ink rollers. The glaze accumulated on the blankets does not allow the ink image to transfer properly, creating a poor image on the printed sheet. In addition, when such presses are shut down, the lithographic plates must be gummed to prevent oxidation of the plates' surface during the shutdown period.
Other drawbacks to acid and gum fountain solutions reside in the fact that these gums cause the growth of algae and fungus mold which may accumulate in the pans and feed lines of the systems. Thus the alkali fountain solutions have been found to be most effective in high speed lithographic printing presses as these have a good replenishing action on the surface of the plate and constantly keep the non-printing area water receptive or hydrophilic.
The present invention relates to a new and unique formulation of a mixture of dry ingredients which may be shipped in bulk to the site of lithographic printing operations. At the printing site, the dry formulation of the present invention, when mixed with water in situ, produces an effective alkali fountain solution for lithographic printing press operation. Use of the dry powder formulation of the present invention with a predetermined quantity of water produces a lithographic fountain solution which is effective to replenish and renew the non-sensitized surface of a lithographic plate and maintain the non-printing area of lithographic printing plates water receptive or hydrophilic. In addition when used in lithographic printing presses the fountain solution produced by the present invention minimizes ink emulsification, eliminates roller stripping and cleans and maintains clean the entire water fountain system, pans, brushes, pumps and tanks of a lithographic press. In addition the fountain solution of the present invention prevents algae buildup or fungus mold from forming in pans or feed lines of the fountain system and greatly reduces linting and piling. In addition the fountain solution formed by the dry powder formulation of the present invention also eliminates the need to gum lithographic plates even on prolonged press shutdown.
The main constituent presently used in commercial lithographic fountain solutions is water. Thus shipment of such solutions to printing press sites is difficult as heavy drums of liquid solution must be shipped. These are bulky, difficult to handle and shipping costs are high. Accordingly, a further beneficial aspect of the dry powder formulation of the present invention resides in the fact that only dry powder in conveniently sized packages or cartridges must be handled and shipped. Thus use of the dry powder formulation for forming a lithographic fountain solution according to the present invention, results in significant cost savings and significantly easier handling in shipment of the dry powder fountain solution formulation. This is true because, the present invention provides a dry powder formulation for a lithographic fountain solution which may be shipped in bulk in its dry state with water, the major constituent by weight, being added at the site of the lithographic printing operation. Thus there is no need to ship large quantities of water which results in significant cost savings and greater ease in handling and shipping.